[RFI] Solar Panel RFI in Kings Park, NY - Update

[Tony Brock-Fisher]

 From my testing, the optimizers internal switchers continue to run (at 
200kHz) anytime the optimizer gets power from the panel - therefore 
during daylight hours. This noise exits the optimizers on both the panel 
leads as well as the DC output leads. This was the reason I retrofitted 
my system with the 3-turn bifilar chokes, in between each optimizer and 
it's panel.

During power generation, the optimizers emit higher levels of noise, 
from both the panel leads and the output leads, at the 200khZ switching 
frequency and harmonics, up through 10 meters or higher.

If the DC output leads have already been properly retrofitted with 
reduced loop area, twisted pair wiring, and chokes, it may now be 
beneficial to add the 3-turn biifilar chokes to the optimizer input 
leads. I noticed a significant improvement in noise when I completed 
this step on my system.

Disconnecting every panel from every optimizer is very labor intensive.  
While this experiment might provide conclusive information about the 
cause of the noise, it won't buy you anything in actual remediation. For 
the same amount of labor, and a moderate additional materials cost, you 
can add the 3-turn bifilar chokes to the optimizers, with the likely 
result of permanently lower noise when the work is completed. This would 
actually be less labor, as the panels can be lifted one at a time, not 
requiring they be removed from the roof, as the chokes are added 
underneath them. Note that this technique has been applied to multiple 
systems with good results each time.

This is like 'peeling the layers of the onion', and you may need to 
address several 'layers' before you get the noise down to an acceptable 
level (which may never get to 'zero noise').

-Tony, K1KP


On 9/14/2018 3:40 PM, Tony wrote:
> All:
>
> Solar Edge shut down my neighbors solar panel system to test for RFI 
> this week. The strength of the noise dropped, but it's still 
> detectable. I'm told that the inverter and optimizers are inactive 
> which my neighbor confirmed.
>
> The problem with this test is that the power supplies within the 
> optimizers remain active since they receive their power from the solar 
> panels. The noise is also typical of the type generated by switching 
> power supplies.
>
> The next logical step would be to disconnect the power supplies from 
> each solar panel to see if the noise goes away. It's something I've 
> asked Solar Edge to do for some time now.
>
> Before I make that request, does anyone have any thoughts on what else 
> could be generating noise with the system turned off?
>
> Tony -K2MO